Article taken from the CPM, written by Martin Rickatson
The principle of companion cropping is beginning to attract interest among OSR growers in the UK, as the advantages of growing beneficial plants within the crop are illustrated by multiple season trials conducted across the UK. This season, thought, a seeder specifically designed for the practice is being trialled by its manufacturer and the agronomy company leading trials of the concept.
Developed in France, the technique of sowing a second crop – usually a mix of deep-rooting clovers and legumes – along with OSR is based on the idea that these crops at first take up and retain surplus soil nitrogen over winter, while also out-competing weeds and suppressing their growth. At the same time, their active rooting systems means they help to improve soil structure and alleviate compaction, opening up the ground for the OSR roots to follow, aiding drainage and structure.
Susceptibility to frosts
Later in the winter their susceptibility to frosts and increasing competition from the OSR plants themselves, which are by then broadening out to fill across the rows, means that if there are sufficient sharp frosts they begin to die off – although a selective herbicide application may be necessary in a mild winter. Their subsequent decomposition releases the nitrogen they had absorbed and locked within them over the winter, when it might otherwise have been leached from the soil.
French plant breeders have researched a number of seed types and mixtures suited to growing alongside OSR but, in UK conditions, trials in Agrovista’s multi-year Growcrop Gold series point to a mixture of common vetch, purple vetch and berseem clover as having the ideal blend of nitrogen uptake, rooting activity and spreading growth.
In addition, these species have low but differing carbon:nitrogen ratios, a characteristic that means the captured nitrogen is released gradually as they decompose over an extended period. With French farmers not allowed to apply artificial nitrogen in autumn, being able to gain an N boost from the natural lock-up and subsequent release of soil N is one of the biggest benefits of the system. For UK OSR growers, the same principle could have the potential for fertiliser savings to be made through more efficient use of soil nitrogen, suggest supporters of the technique.
But the most effective method of establishing the companion crop alongside the OSR has also been the subject of considerable research. The Lincs-based UK arm of Great Plains has been among those at the forefront of this. Following a period of development and trials, the company showed a prototype OSR/companion crop seeder at Jan’s LAMMA.
“We’ve long worded with agronomy companies on development to meet particular agronomic requirements,” says David Holmes of Great Plains UK.
Establishment accuracy
“Our LD low disturbance leg design was a direct result of such collaboration. Increasing interest in the accuracy of OSR establishment at low seed rates meant we began to look at the idea of combining its capabilities with those of zone consolidation and double-disc coulters, to create what would still be a low cost yet more precise method of sowing OSR.
“With continued pressure on OSR herbicides, due mainly to the reduced number available, and environmental concerns around those that remain, more use needs to be made of cultural control of grassweeds, while there’s also increasing awareness of the issue of early season soil erosion from bare soil between plants.
“By designing something that could simultaneously sow OSR and a companion crop, planting it within the same rows or across the whole working width of the implement, our intention was to create a machine that could help meet some of these challenges and exploit the potential cover cropping appears to offer.”
With the LD legs, the company had the ideal starting point to work from, says David Holmes. They’re capable of restructuring to depth and operate through previous plant material while disturbing the surface as little as possible.
“That was important in terms of not creating unnecessary blackgrass germination – any weed seeds we wanted to leave on top to ensure they’re exposed to herbicides. But we did want to create a small amount of surface tilth into which the OSR, and the companion crop mix could be placed. To get good seed-to-soil contact we wanted to ensure that the naturally-formed fines on the soil surface were retained there, to make best use of them when placing the OSR and companion crop seed.
“Essentially, what we were looking to create was something that combined the features of our ST-Bar with low-disturbance loosening legs with press wheels and a coulter system. But we wanted to loosen the ground and scratch the soil surface only where necessary, instead of across the whole profile.
“On the back of that, we wanted to be able to offer something that could place the OSR and companion crop seed mix in rows, using a conventional metering system, or allow the operator to disperse the companion crop seed across the whole working width if preferred.”
Working in conjunction with farmers and agronomists, what Great Plains’ designers created was a 3m-wide machine with leading legs, following scratch tines and individual steel rollers. Behind this come double-disc openers, followed by pairs of narrow, solid rubber consolidation wheels pressing the soil and controlling depth.
“The five legs are designed to provide conditioning of the rooting zone, but not work as deep as a subsoiler,” explains David Holmes.
“Spaced at 575mm and equipped with a new design of mini-wing points, the legs are designed to break up any surface compaction, working down to a maximum 250mm depth. They create a vertical rooting zone that the plants can exploit before they’re sufficiently developed to begin making their own patch. Each leg is protected by a ‘Krava’ spring breakback system.
“These are then followed by individual light-duty levelling boards, equipped with pairs of small tines which serve to create a small amount of surface tilth if required between the tines and zone consolidation area.
“Immediately behind them is the new design zonal roller. Early on in the drill’s development, we decided to design small, flat-surfaced consolidation wheels made from steel, to help avoid soil adhesion. They press a 280mm patch behind each tine, and wheel drive in damp soils is ensured by the toothed rims on the sides of each roller, which press lightly into the soil.
Accurate depth control
“Having a properly loosened and then consolidated upper soil profile allows us to achieve much more accurate depth control when the OSR is planted, and greater seeding precision plus improved evenness of emergence as a result. Meanwhile, the soil between the LD legs is left undisturbed for minimal stimulation of weed growth when the light levelling board isn’t required.”
Following this come the seed furrow openers, in the form of the firm’s ‘00’ double-disc design, adopted from its Centurion grain drill and other Great Plains seeders. The firm’s engineering team believes this gives the best possible format for operating in high trash conditions.
The coulter pairs are set 100mm to each side of each leg, and between the 330mm x 4mm offset double discs is a knife coulter fed by seed metered into pipes from the two hoppers on the machine – one for the OSR and one for the cover crop mix. Shortly before each disc pair, these two tubes merge and blend the two sets of seed, with knife coulters between the discs guiding the seed to the bottom of the furrow, with a flap preventing it from bouncing upwards. A T-handle adjuster alters the press-wheel height to control the seeding depth of the disc coulter it’s paired with.
Alternatively, if an overall spread of companion seed is preferred, the pipes from the companion crop seed hopper can be routed to just behind each roller, with the seed dropped onto the surface, leaving only the OSR to be sown in rows by the double-disc coulters.
“This is still very much a prototype design, and we’re also looking at other ideas we may be able to incorporate into the machine,” says David Holmes.
“For example, it’s possible to incorporate a fertiliser system, putting product down either behind or in front of the seed coulters. It’s also possible we could develop a retrofit version to be used for farmers who already have an existing ST Bar.
“We’ve had a good level of enquiries and interest since LAMMA, and if sustained, by trials results this summer we should then have a final specification for release.”
Companion crop experiments have been part of Agrovista’s long-running Growcrop Gold OSR trials programme since the 2012-13 season, when they were included to evaluate the concept’s potential across five trials sites in Norfolk, Glos, Shrops, Yorks and Angus. It’s only this season, though, that the purpose-built Great Plains 00 Series double-disc opener drill has been included in the programme, planting a blend of common vetch, purple vetch and berseem clover along with the OSR.
“Previously, we had been establishing companion crops almost exclusively with a Great Plains Simba DTX with two seed boxes fitted,” explains Niall Atkinson, who co-ordinates the Growcrop Gold trials for Agrovista.
“OSR from one was dropped behind the DTX’s DD rings in 55cm rows, each centred on the leg patch and the groove left by the press ring. Companion plants from the second hopper were then broadcast between the OSR rows.
“But we’d been banging the drum for some time to get a machinery manufacturer to develop an implement that would combine loosening with a coulter system for one-pass OSR establishment with greater precision. The more even establishment such as system should achieve has implications for seed and herbicide costs.
“Among others who have tried the technique – and there are a number of farmers across the country now using it – some use a front linkage-mounted distributor, or a separate pass ahead of the OSR seeder, to put down the companion crop before the OSR is sown. The difficulty in mixing the seeds and sowing them from one hopper is that, while small batches of up to 4-5ha worth of seed cause no problems, quantities greater than this tend to separate as the seed box empties. So we were keen to work with Great Plains to trial the system on which they’ve been working.”
The Great Plains seeder was used for the first time in the trial in summer 2014, sowing trial plots at all five sites. With the new machine, improved establishment precision of the OSR has had some obvious benefits this far into the season, says Niall Atkinson, and he hopes this’ll translate into yield advantages at harvest.
Room to grow
“More precise placement than with a conventional seeder system means there’s also more even establishment of the companion crop taking up the spaces in between, so plants have even room to grow and intercept light.
“Meanwhile, the legs appear to clear sufficient trash from their path to prevent material from impeding OSR or companion crop growth.”
With trials suggesting ideal OSR seed rates can, in many situations, be as low as 15 seeds per metre row length, to give 10-12 established plants, it’s essential to ensure every plant grows, so getting the proportions and the precision right is important, he says.
“Evidence suggests we still have some work to do on ideal seed rates, but it would appear that there’s scope to cut back those for the companion crop mix over what we’re currently using. Work to date has led to the development of two-seed mixes to match either in-row or overall companion-crop systems.
“PC1, a blend of common vetch, purple vetch and berseem clover, is designed for overall application at 20kg/ha as an establishment aid and on fertile sites to capture nutrients over winter and release them back to the crop in spring. For in-row application, there’s an alternative PC3 blend, which can be applied at 5-7.5kt/ha, and is best suited as an establishment aid for wide row crops on heavier soils or where trash levels are high.”
There’s also more work to be done one measuring the efficacy of the natural soil loosening provided by companion crop rooting, he suggests.
“The rooting effects of berseem clover in particular do a very good job on making the soil more friable to significant depth, to allow the OSR to exploit this as the companion crop dies back.”
Last year, trials at the Cockle Park trial site in Northumberland saw plots planted with PC1 companion plants average 3.55t/ha, with admix of 0.7% and oil content of 45.7%.
Comparative figures without the PC1 were 3.08t/ha, 2.7% and 44.5%. At the Stoughton site in Leics, trials sown at 28 seeds/m² (15 seeds/m row) yielded 4.6t/ha when planted alone, 4.54t/ha when placed with companion plants in the row, and 5.10t/ha when sown with companion plants between the rows.
The principle of companion cropping is beginning to attract interest among OSR growers in the UK, as the advantages of growing beneficial plants within the crop are illustrated by multiple season trials conducted across the UK. This season, thought, a seeder specifically designed for the practice is being trialled by its manufacturer and the agronomy company leading trials of the concept.
Developed in France, the technique of sowing a second crop – usually a mix of deep-rooting clovers and legumes – along with OSR is based on the idea that these crops at first take up and retain surplus soil nitrogen over winter, while also out-competing weeds and suppressing their growth. At the same time, their active rooting systems means they help to improve soil structure and alleviate compaction, opening up the ground for the OSR roots to follow, aiding drainage and structure.
Susceptibility to frosts
Later in the winter their susceptibility to frosts and increasing competition from the OSR plants themselves, which are by then broadening out to fill across the rows, means that if there are sufficient sharp frosts they begin to die off – although a selective herbicide application may be necessary in a mild winter. Their subsequent decomposition releases the nitrogen they had absorbed and locked within them over the winter, when it might otherwise have been leached from the soil.
French plant breeders have researched a number of seed types and mixtures suited to growing alongside OSR but, in UK conditions, trials in Agrovista’s multi-year Growcrop Gold series point to a mixture of common vetch, purple vetch and berseem clover as having the ideal blend of nitrogen uptake, rooting activity and spreading growth.
In addition, these species have low but differing carbon:nitrogen ratios, a characteristic that means the captured nitrogen is released gradually as they decompose over an extended period. With French farmers not allowed to apply artificial nitrogen in autumn, being able to gain an N boost from the natural lock-up and subsequent release of soil N is one of the biggest benefits of the system. For UK OSR growers, the same principle could have the potential for fertiliser savings to be made through more efficient use of soil nitrogen, suggest supporters of the technique.
But the most effective method of establishing the companion crop alongside the OSR has also been the subject of considerable research. The Lincs-based UK arm of Great Plains has been among those at the forefront of this. Following a period of development and trials, the company showed a prototype OSR/companion crop seeder at Jan’s LAMMA.
“We’ve long worded with agronomy companies on development to meet particular agronomic requirements,” says David Holmes of Great Plains UK.
Establishment accuracy
“Our LD low disturbance leg design was a direct result of such collaboration. Increasing interest in the accuracy of OSR establishment at low seed rates meant we began to look at the idea of combining its capabilities with those of zone consolidation and double-disc coulters, to create what would still be a low cost yet more precise method of sowing OSR.
“With continued pressure on OSR herbicides, due mainly to the reduced number available, and environmental concerns around those that remain, more use needs to be made of cultural control of grassweeds, while there’s also increasing awareness of the issue of early season soil erosion from bare soil between plants.
“By designing something that could simultaneously sow OSR and a companion crop, planting it within the same rows or across the whole working width of the implement, our intention was to create a machine that could help meet some of these challenges and exploit the potential cover cropping appears to offer.”
With the LD legs, the company had the ideal starting point to work from, says David Holmes. They’re capable of restructuring to depth and operate through previous plant material while disturbing the surface as little as possible.
“That was important in terms of not creating unnecessary blackgrass germination – any weed seeds we wanted to leave on top to ensure they’re exposed to herbicides. But we did want to create a small amount of surface tilth into which the OSR, and the companion crop mix could be placed. To get good seed-to-soil contact we wanted to ensure that the naturally-formed fines on the soil surface were retained there, to make best use of them when placing the OSR and companion crop seed.
“Essentially, what we were looking to create was something that combined the features of our ST-Bar with low-disturbance loosening legs with press wheels and a coulter system. But we wanted to loosen the ground and scratch the soil surface only where necessary, instead of across the whole profile.
“On the back of that, we wanted to be able to offer something that could place the OSR and companion crop seed mix in rows, using a conventional metering system, or allow the operator to disperse the companion crop seed across the whole working width if preferred.”
Working in conjunction with farmers and agronomists, what Great Plains’ designers created was a 3m-wide machine with leading legs, following scratch tines and individual steel rollers. Behind this come double-disc openers, followed by pairs of narrow, solid rubber consolidation wheels pressing the soil and controlling depth.
“The five legs are designed to provide conditioning of the rooting zone, but not work as deep as a subsoiler,” explains David Holmes.
“Spaced at 575mm and equipped with a new design of mini-wing points, the legs are designed to break up any surface compaction, working down to a maximum 250mm depth. They create a vertical rooting zone that the plants can exploit before they’re sufficiently developed to begin making their own patch. Each leg is protected by a ‘Krava’ spring breakback system.
“These are then followed by individual light-duty levelling boards, equipped with pairs of small tines which serve to create a small amount of surface tilth if required between the tines and zone consolidation area.
“Immediately behind them is the new design zonal roller. Early on in the drill’s development, we decided to design small, flat-surfaced consolidation wheels made from steel, to help avoid soil adhesion. They press a 280mm patch behind each tine, and wheel drive in damp soils is ensured by the toothed rims on the sides of each roller, which press lightly into the soil.
Accurate depth control
“Having a properly loosened and then consolidated upper soil profile allows us to achieve much more accurate depth control when the OSR is planted, and greater seeding precision plus improved evenness of emergence as a result. Meanwhile, the soil between the LD legs is left undisturbed for minimal stimulation of weed growth when the light levelling board isn’t required.”
Following this come the seed furrow openers, in the form of the firm’s ‘00’ double-disc design, adopted from its Centurion grain drill and other Great Plains seeders. The firm’s engineering team believes this gives the best possible format for operating in high trash conditions.
The coulter pairs are set 100mm to each side of each leg, and between the 330mm x 4mm offset double discs is a knife coulter fed by seed metered into pipes from the two hoppers on the machine – one for the OSR and one for the cover crop mix. Shortly before each disc pair, these two tubes merge and blend the two sets of seed, with knife coulters between the discs guiding the seed to the bottom of the furrow, with a flap preventing it from bouncing upwards. A T-handle adjuster alters the press-wheel height to control the seeding depth of the disc coulter it’s paired with.
Alternatively, if an overall spread of companion seed is preferred, the pipes from the companion crop seed hopper can be routed to just behind each roller, with the seed dropped onto the surface, leaving only the OSR to be sown in rows by the double-disc coulters.
“This is still very much a prototype design, and we’re also looking at other ideas we may be able to incorporate into the machine,” says David Holmes.
“For example, it’s possible to incorporate a fertiliser system, putting product down either behind or in front of the seed coulters. It’s also possible we could develop a retrofit version to be used for farmers who already have an existing ST Bar.
“We’ve had a good level of enquiries and interest since LAMMA, and if sustained, by trials results this summer we should then have a final specification for release.”
Companion crop experiments have been part of Agrovista’s long-running Growcrop Gold OSR trials programme since the 2012-13 season, when they were included to evaluate the concept’s potential across five trials sites in Norfolk, Glos, Shrops, Yorks and Angus. It’s only this season, though, that the purpose-built Great Plains 00 Series double-disc opener drill has been included in the programme, planting a blend of common vetch, purple vetch and berseem clover along with the OSR.
“Previously, we had been establishing companion crops almost exclusively with a Great Plains Simba DTX with two seed boxes fitted,” explains Niall Atkinson, who co-ordinates the Growcrop Gold trials for Agrovista.
“OSR from one was dropped behind the DTX’s DD rings in 55cm rows, each centred on the leg patch and the groove left by the press ring. Companion plants from the second hopper were then broadcast between the OSR rows.
“But we’d been banging the drum for some time to get a machinery manufacturer to develop an implement that would combine loosening with a coulter system for one-pass OSR establishment with greater precision. The more even establishment such as system should achieve has implications for seed and herbicide costs.
“Among others who have tried the technique – and there are a number of farmers across the country now using it – some use a front linkage-mounted distributor, or a separate pass ahead of the OSR seeder, to put down the companion crop before the OSR is sown. The difficulty in mixing the seeds and sowing them from one hopper is that, while small batches of up to 4-5ha worth of seed cause no problems, quantities greater than this tend to separate as the seed box empties. So we were keen to work with Great Plains to trial the system on which they’ve been working.”
The Great Plains seeder was used for the first time in the trial in summer 2014, sowing trial plots at all five sites. With the new machine, improved establishment precision of the OSR has had some obvious benefits this far into the season, says Niall Atkinson, and he hopes this’ll translate into yield advantages at harvest.
Room to grow
“More precise placement than with a conventional seeder system means there’s also more even establishment of the companion crop taking up the spaces in between, so plants have even room to grow and intercept light.
“Meanwhile, the legs appear to clear sufficient trash from their path to prevent material from impeding OSR or companion crop growth.”
With trials suggesting ideal OSR seed rates can, in many situations, be as low as 15 seeds per metre row length, to give 10-12 established plants, it’s essential to ensure every plant grows, so getting the proportions and the precision right is important, he says.
“Evidence suggests we still have some work to do on ideal seed rates, but it would appear that there’s scope to cut back those for the companion crop mix over what we’re currently using. Work to date has led to the development of two-seed mixes to match either in-row or overall companion-crop systems.
“PC1, a blend of common vetch, purple vetch and berseem clover, is designed for overall application at 20kg/ha as an establishment aid and on fertile sites to capture nutrients over winter and release them back to the crop in spring. For in-row application, there’s an alternative PC3 blend, which can be applied at 5-7.5kt/ha, and is best suited as an establishment aid for wide row crops on heavier soils or where trash levels are high.”
There’s also more work to be done one measuring the efficacy of the natural soil loosening provided by companion crop rooting, he suggests.
“The rooting effects of berseem clover in particular do a very good job on making the soil more friable to significant depth, to allow the OSR to exploit this as the companion crop dies back.”
Last year, trials at the Cockle Park trial site in Northumberland saw plots planted with PC1 companion plants average 3.55t/ha, with admix of 0.7% and oil content of 45.7%.
Comparative figures without the PC1 were 3.08t/ha, 2.7% and 44.5%. At the Stoughton site in Leics, trials sown at 28 seeds/m² (15 seeds/m row) yielded 4.6t/ha when planted alone, 4.54t/ha when placed with companion plants in the row, and 5.10t/ha when sown with companion plants between the rows.